The permeability of a material relates to the ability of a fluid and fluid transmissible particles to penetrate the material. Different materials have different permeabilities. Some materials are impervious to some fluids, that is, they are unable to be penetrated by those fluids. Some materials are pervious to various fluids. Of course, most materials are semi-impervious to various fluids.
In an effort to protect workers who are exposed to bloodborne pathogens or other infectious materials at work, the Occupational Safety and Health Agency (OSHA) has set requirements for the penetrability of protective clothing by bloodborne pathogens and/or other infectious materials; e.g., the Bloodborne Pathogen Standard of Dec. 6, 1991.
To determine the permeability of various materials, researchers have been trying to find a simple, universal test method and apparatus. One simple pass/fail penetration test is referred to as the Elbow Lean Test. In this test, a conventional rubber stamp ink pad is saturated with a challenge fluid; that is, the fluid with which the permeability of a particular material is to be tested. The test material is then placed over the pad with the outside down against and in contact with the stamp pad. A person then leans on the pad with their elbow. If fluid is detected on the inside surface of the material, the material fails the test. If no fluid is detected, the material passes the test. This is a very general pass/fail test as the force exerted by one's elbow may vary greatly; e.g., twenty to seventy pounds.
Recently, there has been substantial concern over the safety of healthcare professions and others who come in contact with blood that may contain pathogens such as hepatitis B virus (HBV) and human immunodeficiency virus (HIV), as well as other infectious materials.
In some penetration tests, the permeability of various pathogens or other fluid transmitted particles is being tested. In these cases, alternative detection means other than visual detection is used to determine if penetration has occurred. For example, chemical detectors, radioactive detectors, etc. might be used. In many cases alternative detectors are used where the fluid is colorless and cannot be visually detected. If the fluid is colorless, dyes or other coloring agents can be added to aid in the visual detection process.
Material penetration testing is replete with testers which use pressurized or impact fluid penetration mechanisms to demonstrate material liquid penetration resistance. These tests and testers include the following: INDA Water Spray Test IST 80.1-70 (R82), INDA Impact Penetration Test IST 80.5-70 (R82), INDA Hydro Pressure Test IST 80.6-70 (R82 ), INDA Saline Repellency Test IST 80.7-70 (R82), AATCC Water Resistance: Suter Hydrostatic Pressure Test 127-1985, AATCC Spray Rating Test 22-1985, ATTCC Rain Test 35-1985, Federal Gov. Water Resistance of Coated Cloth; High Range, Hydrostatic Pressure Method, ASTM Mullen Hydrostatic test D751, ASTM Standard Test Method For Resistance of Protective Clothing To Penetration By Liquids F903-90, ASTM Emergency Standard Test Method For Resistance Of Protective Clothing Materials To Synthetic Blood F23.40.01, and ASTM Emergency Standard Test Method For Resistance Of Protective Clothing Materials To Penetration By Bloodborne Pathogens Using Viral Penetration As A Test System F23.40.02.
The testers used in these tests are typically complicated in design, cumbersome to set up, time consuming to use, difficult to clean, semi-portable, not suitable for field use, expensive, and based on subjecting test materials to contained hydrostatic pressures which are not representative of actual use conditions experienced by wearers of protective clothing where free flowing fluids on the outer surfaces of a material are momentarily pressurized against the clothing and skin of the wearer by fingers, elbows, and other objects. A good example of this type of testing is American Society for Testing and Materials (ASTA) F 903-90 standard test method for resistance of protective clothing materials to penetration by liquids. This test requires that the material to be tested is mounted in a test cell which in turn is attached to an air pressure line. The challenge fluid is then exposed to a predetermined air pressure for a predetermined period of time.
The contained hydrostatic pressure methods also unnaturally expand, stretch, and pull apart the material structure thereby causing failure of the liquid/pathogen barrier and avoidable negative results in both visible liquid and pathogen penetration tests. Therefore, the contained hydrostatic pressure method is too rigorous for 90% of the protective products market and unnecessarily expensive for manufacturers and consumers.
The present invention solves many of the problems associated with the prior art.